In electrophotography, a latent image is created on the surface of an imaging member such as a photoconducting material by selectively exposing areas of the surface to light. A difference in electrostatic charge density is created between those areas on the surface which are exposed to light and those areas on the surface which are not exposed to light. The latent electrostatic image is developed into a visible image by electrostatic toners. The toners are selectively attracted to either the exposed or unexposed portions of the photoconductor surface, depending on the relative electrostatic charges on the photoconductor surface, the development electrode and the toner.
The use of charge transport compounds or molecules in imaging members such as electrophotographic photoconductors is well known in the art. Typically, a layered electrophotographic photoconductor comprises a metal ground plane member on which a charge generation layer (CGL) and a charge transport layer (CTL) are coated. When a hole transport layer is formed on the top of the charge generation layer, the photoconductor surface typically is negatively charged. Conversely, when the charge generation layer is formed on the top of the charge transport layer, the photoconductor surface typically is positively charged. Generally, the charge generation layer comprises a polymeric binder containing a charge generation compound or molecule while the charge transport layer comprises a polymeric binder containing a charge transport compound or molecule. The charge generation compounds within the CGL are sensitive to image-forming radiation and photogenerate electron-hole pairs within the CGL as a result of such radiation. The CTL is usually transparent to the image-forming radiation and the charge transport compounds serve to transport holes to the surface of the photoconductor. Photoconductors of this type are disclosed in the Adley et al U.S. Pat. No. 5,130,215 and the Balthis et al U.S. Pat. No. 5,545,499.
The use of hydrazone compounds as charge transport compounds or molecules in a charge transport layer of a photoconductive member is also known in the art as disclosed in the Anderson et al U.S. Pat. Nos. 4,150,987 and 4,362,798, the Ishikawa et al U.S. Pat. Nos. 4,390,611 and 4,413,045, and the Sakai et al U.S. Pat. No. 4,387,147. A hydrazone compound which is commonly employed in charge transport layers comprises 4-(diethylamino)benzaldehyde diphenylhydrazone (DEH). Photoconductors having good sensitivity have been obtained with the use of hydrazone compounds such as DEH as the charge transport compound of a charge transport layer. However, as photoconductors having improved performance or extended photoconductor life are continually desired, there is a continuing need for the development of new materials to meet these demands.